Color ink jet recording method

ABSTRACT

A color ink jet recording method is provided which can provide a color image having a higher quality and attain a print quality of a black ink comparable to that of the conventional monochrome print. A color ink jet recording method for printing on a recording medium, comprising the steps of: when a portion to be black is in contact with a color portion in a color image to be formed, printing, first, at least one color ink on a portion which is a part of the portion to be black and is in contact with the color portion on the recording medium, then printing a black ink on a portion which is to be black and is partially printed with the color ink according to the previous step, wherein a plural of color inks having a surface tension at 20° C. of less than 40 dyn/cm and a black ink having a surface tension at 20° C. of 40 dyn/cm or more.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method for forming a color image byan ink jet recording system.

2. Background Art

Color images are, in general, formed by employing individual colors ofyellow, magenta, cyan and black. When dots of these colors are formed byan ink jet recording system, color mixing or flow of one color portioninto other color portion in a portion where different colors (inparticular, a black portion and a color portion) were in contact witheach other means a deterioration in color images. Various proposals havebeen made for providing sharp color images as follows.

For example, Japanese Patent Laid-Open Nos. 197776/1985, 197777/1985 and197778/1985 disclose that the deterioration in color images can beprevented by making compositions or properties of inks equal. Thepublications disclose that the deterioration in color images can beprevented by rendering inks equal to each other in respect of the timeof fixation and degree of blurring on a recording material. In the inksdescribed in the publications, however, the degree of blurring cannot besufficiently reduced so that there is room for improvement in the colorimages. Furthermore, even in a color printer, a black print is desiredto have a quality comparable to print by a conventional monochromeprinter. However, the quality of black print formed with a black inkdescribed in the above publications was inferior to that of printsformed with a monochrome printer.

Japanese Patent Laid-Open No. 41171/1991 discloses a method in whichprinting with a water-base color ink having a surface tension of 30 to40 mN/m precedes printing with a water-base black ink having a surfacetension of 45 to 73 mN/m. The publication describes that it is possibleeven in a color printer to realize a good black print having qualitywhich is comparable to that of a conventional black print. However, evenin this method, it is observed that the black ink "flows into" the colorink portion at a portion where the black portion is in close vicinity tothe color portion. As the result, the sharpness of the outline of theblack portion becomes unsatisfactory. This is because, when a portion tobe black is in contact with the colored portion, there occurs adifference in penetrability of ink between the colored portion where aprint has been already formed with a color ink and the portion where ablack print is to be formed. Specifically, an ink is more easilypenetrated into an portion where a print has been already formed with acolor ink than into a portion where no print is formed yet (i.e., aportion to be rendered black). Therefore, when a black ink is applied toa portion in contact with a portion where a color ink has already beenapplied, the black ink is drawn or flows into the portion where thecolor ink has been applied. As the result, the sharpness of the colorimage becomes unsatisfactory. In order to prevent this phenomenon, itmay be necessary to use special recording paper having a coated surface.

Thus, in the formation of a color image by an ink jet recording system,there is room for improvement.

SUMMARY OF THE INVENTION

Accordingly, an object of the present invention is to provide an ink jetrecording method which can provide a high-quality color image.

Another object of the present invention is to provide a color ink jetrecording method which can provide a black print-having a qualitycomparable to the conventional monochrome print.

The present inventors have now found that the objects can be attained byfirst printing a color ink to a portion to be rendered black and thenprinting a black ink to the portion. The present invention has been madebased on this finding.

Specifically, the ink jet recording method for printing on a recordingmedium according to the present invention comprises the steps of:

when a portion to be black is in contact with a color portion in a colorimage to be formed, printing first at least one color ink on a portionwhich is a part of the portion to be black and is in contact with thecolor portion on a recording medium,

printing a black ink on a portion which is to be black and is partiallyprinted with the color ink according to the previous step,

wherein a plural of color inks having a surface tension at 20° C. ofless than 40 dyn/cm and a black ink having a surface tension at 20° C.of 40 dyn/cm or more.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of a portion where a black portion is incontact with a color portion, to which method according to the presentinvention is preferably applied;

FIGS. 2(a)-2(d) is a schematic view showing the printing steps accordingto the method of the present invention; and

FIGS. 3a-3c is a schematic view showing the printing steps according aconventional method.

PREFERRED EMBODIMENTS OF THE INVENTION

In respect of the formation of a color image using a plural of colorinks, preferably yellow, magenta and cyan inks, and a black ink, theconventional color ink jet recording methods may be employed as the inkjet recording method according to the present invention, except formodifications which will be descried later.

The method according to the present invention is applied to a portionwhere a black portion is in contact with a color portion in a colorimage to be formed on a recording medium. For example, the presentinvention has advantages when a stripe pattern as shown in FIG. 1, inwhich a black portion 1 is adjacent to a color portion (for example, ayellow portion) 2, is formed.

FIG. 2 is a schematic view showing the printing steps at a portion 3(hereinafter referred to as "boundary") where the black portion 1 andthe color portion 2 in FIG. 1 are in contact with each other. Accordingto the method of the present invention, first, color ink droplets 4 areapplied to a region corresponding to a color portion 2 with an ink jetrecording system (FIG. 2 (a)). In this case, the color ink is alsoapplied to a region of a black portion 1 beyond the boundary 3. Theapplied color ink is penetrated into the recording medium (region 5 inFIG. 2 (b)). Black ink droplets 6 are next applied to a region of theblack portion 1 with the ink jet recording system (FIG. 2 (c)). On therecording medium, there is no difference in the penetrability of the inkbetween both sides of the boundary 3. Therefore, the force by which theapplied black ink is drawn beyond the boundary 3 becomes relativelylower than the force by which the ink is vertically drawn into therecording medium. Consequently, there is no possibility that the blackink is flowed into the color portion remarkably beyond the boundary 3(region 6 in FIG. 2 (d)). This enables a sharp color image to berealized.

On the other hand, as shown in FIGS. 3a, 3b, 3c, in a conventionalprinting method, there is a difference in the penetrability of the inkinto the recording medium between both sides of the boundary 3. Theblack ink is thus drawn into the portion to be colored beyond theboundary 3, which renders the color image dull. Accordingly, the presentinvention can effectively prevent the phenomenon that the black inkflows into the color portion beyond the boundary 3 as found in theconventional printing method as shown in FIG. 3.

As is apparent from the above, in the present invention, it is primarilyimportant not to cause a difference in the penetrability of the ink intothe recording medium between both sides of the boundary when a portionto be black is in contact with a portion to be colored. Therefore, thereis no particular limitation on the color of the ink applied to a portionto be rendered black prior to applying a black ink to the portion.However, it is preferred to use an ink having the same color as thecolor portion in contact with the portion to be rendered black. Forexample, in the case of a strip pattern comprising yellow and black asshown in FIG. 1, the color of the ink applied beyond the boundary 3 ispreferably yellow.

According to a preferred embodiment of the present invention, the weightratio of black ink to color ink per dot is preferably in the range of10:1 to 1:1, still preferably in the range of 5:1 to 1:1. When theweight ratio is in the range, the dot diameter of the black ink can bemade identical to that of the color ink. When the weight ratio of theblack ink to the color ink is less than 1, no black dot having asufficient density can be provided, so that no sharp image can beformed. On the other hand, when the weight ratio of the black ink to thecolor ink exceeds 10, the dot of the black ink becomes excessivelylarger than the previously formed dot of the color ink, whichunfavorably leads to a possibility that blurring occurs. The weightratio in the above range is advantageous also in that the drying rate ofthe black ink can be made identical to that of the color ink.

In the method according to the present invention, the color ink may havea surface tension at 20° C. of less than 40 dyn/cm, preferably 25 to 35dyn/cm, still preferably 26 to 32 dyn/cm, and the black ink may have asurface tension at 20° C. of 40 dyn/cm or more, preferably 45 to 65dyn/cm, still preferably 50 to 60 dyn/cm. The composition of the ink isnot particularly limited so far as the surface tensions are in the aboveranges. Some conventional inks may be preferably used.

Since a difference in the penetrability into the recording medium,fixation time, etc. between color inks is not much favorable, it ispreferred for the surface tensions of the color inks to be substantiallythe same. Therefore, still preferably, the color inks have the same orsubstantially the same composition except for the colorant.

Preferred examples of the colorant of the ink used in the methodaccording to the present invention include water-soluble dyes, andspecific examples thereof include:

C.I. Direct Red 2, 4, 9, 23, 26, 31, 39, 62, 63, 72, 75, 76, 79, 80, 81,83, 84, 89, 92, 95, 111, 173, 184, 207, 211, 212, 214, 218, 221, 223,224, 225, 226, 227, 232, 233, 240, 241, 241, 243 and 247;

C.I. Direct Violet 7, 9, 47, 48, 51, 66, 90, 93, 94, 95, 98, 100 and101;

C.I. Direct Yellow 8, 9, 11, 12, 27, 28, 29, 33, 35, 39, 41, 44, 50, 53,58, 59, 68, 86, 87, 93, 95, 96, 98, 100, 106, 108, 109, 110, 130, 132,142, 144, 161 and 163;

C.I. Direct Blue 1, 10, 15, 22, 25, 55, 67, 68, 71, 76, 77, 78, 80, 84,86, 87, 90, 98, 106, 108, 109, 151, 156, 158, 159, 160, 168, 189, 192,193, 194, 199, 200, 201, 202, 203, 207, 211, 213, 214, 218, 225, 229,236, 237, 244, 248, 249, 251, 252, 264, 270, 280, 288, 289 and 291;

C.I. Direct Black 9, 17, 19, 22, 32, 51, 56, 62, 69, 77, 80, 91, 94, 97,108, 112, 113, 114, 117, 118, 121, 122, 125, 132, 146, 154, 166, 168,173 and 199;

C.I. Acid Red 35, 42, 52, 57, 62, 80, 82, 111, 114, 118, 119, 127, 128,131, 143, 151, 154, 158, 249, 254, 257, 261, 263, 266, 289, 299, 301,305, 336, 337, 361, 396 and 397;

C.I. Acid Violet 5, 34, 43, 47, 48, 90, 103 and 126;

C.I. Acid Yellow 17, 19, 23, 25, 39, 40, 42, 44, 49, 50, 61, 64, 76, 79,110, 127, 135, 143, 151, 159, 169, 174, 190, 195, 196, 197, 199, 218,219, 222 and 227;

C.I. Acid Blue 9, 25, 40, 41, 62, 72, 76, 78, 80, 82, 92, 106, 112, 113,120, 127, 129, 138, 143, 175, 181, 205, 207, 220, 221, 230, 232, 247,258, 260, 264, 271, 277, 278, 279, 280, 288, 290 and 326;

C.I. Acid Black 7, 24, 29, 48, 52 and 172;

C.I. Reactive Red 3, 13, 17, 19, 21, 22, 23, 24, 29, 35, 37, 40, 41, 43,45, 49 and 55;

C.I. Reactive Violet 1, 3, 4, 5, 6, 7, 8, 9, 16, 17, 22, 23, 24, 26, 27,33 and 34;

C.I. Reactive Yellow 2, 3, 13, 14, 15, 17, 18, 23, 24, 25, 26, 27, 29,35, 37, 41 and 42;

C.I. Reactive Blue 2, 3, 5, 8, 10, 13, 14, 15, 17, 18, 19, 21, 25, 26,27, 28, 29 and 38;

C.I. Reactive Black 4, 5, 8, 14, 21, 23, 26, 31, 32 and 34;

C.I. Basic Red 12, 13, 14, 15, 18, 22, 23, 24, 25, 27, 29, 35, 36, 38,39, 45 and 46;

C.I. Basic Violet 1, 2, 3, 7, 10, 15, 16, 20, 21, 25, 27, 28, 35, 37,39, 40 and 48;

C.I. Basic Yellow 1, 2, 4, 11, 13, 14, 15, 19, 21, 23, 24, 25, 28, 29,32, 36, 39 and 40;

C.I. Basic Blue 1, 3, 5, 7, 9, 22, 26, 41, 45, 46, 47, 54, 57, 60, 62,65, 66, 69 and 71;

C.I. Basic Black 8.

It is also preferable to use pigments, and examples of the pigmentsinclude inorganic pigments, such as carbon black, and organic pigments,such as insoluble azo pigments, soluble azo pigments, phthalocyaninepigments, isoindolinone pigments, quinacridone pigments andperinone-perylene pigments. When the pigments are used as the colorant,the particle diameter is preferably 25 μm or less, still preferably 1 μmor less.

According to a preferred embodiment of the present invention, the blackink contains a pigment as the colorant, and the color inks contain awater-soluble dye as the colorant.

The content of the colorant in the ink can be properly determined bytaking,for instance, the printing density, clogging, jetting propertiesinto consideration. In particular, when the black ink contains apigment, the amount of the pigment added is preferably in the range ofabout 1 to 30% by weight, still preferably in the range of about 3 to12% by weight, based on the ink. When the ink contains a water-solubledye, the amount of the water-soluble dye added is preferably in therange of 0.3 to 25% by weight, still preferably in the range of 1 to 10%by weight, based on the ink.

When the pigment is used as the colorant, it is preferred to add adispersant for the purpose of sufficiently dispersing the pigment. It ispreferred to use as the dispersant known polymeric dispersants andsurfactants commonly used for dispersing pigments in conventional inkscontaining pigments.

Preferred examples of the polymeric dispersant include natural polymers,and specific examples thereof include proteins such as glue, gelatin,casein and albumin; natural rubbers such as gum arabic and tragacanthrubber; glucosides such as saponin; alginic acid and alginic acidderivatives such as alginic acid propylene glycol ester, alginic acidtriethanolamine and ammonium alginate; and cellulose derivatives such asmethyl cellulose, carboxymethyl cellulose, polyethylene oxide,hydroxyethyl cellulose and ethylhydroxyethyl cellulose. Furtherpreferred examples of the polymeric dispersant include syntheticpolymers, and specific examples thereof include polyvinyl alcohols;polyvinyl pyrrolidones; acrylic resins such as polyacrylic acid, acrylicacid/acrylonitrile copolymer, potassium acrylate/acrylonitrilecopolymer, vinyl acetate/acrylic ester copolymer and acrylic acid/alkylacrylate copolymer; styrene/acrylic resins such as styrene/acrylic acidcopolymer, styrene/methacrylic acid copolymer, styrene/methacrylicacid/alkyl acrylate copolymer, styrene/a-methylstyrene/acrylic acidcopolymer and styrene/a-methylstyrene/acrylic acid/alkyl acrylatecopolymer; styrene/maleic acid; styrene/maleic anhydride;vinylnaphthalene/acrylic acid copolymer; vinylnaphthalene/maleic acidcopolymer; and vinyl acetate copolymers such as vinyl acetate/ethylenecopolymer, vinyl acetate/fatty acid/vinylethylene copolymer, vinylacetate/maleic ester copolymer, vinyl acetate/crotonic acid copolymer,vinyl acetate/acrylic acid copolymer. Among them, a copolymer of amonomer having a hydrophobic group with a monomer having a hydrophilicgroup and a polymer comprising a monomer having both a hydrophobic groupand a hydrophilic group are particularly preferred.

Preferred examples of the surfactant as the dispersant include anionicsurfactants such as salts of fatty acid, salts of higheralkyldicarboxylic acids, salts of sulfuric acid ester of higheralcohols, salts of higher alkylsulfonic acids, condensates of higherfatty acids with amino acids, salts of sulfosuccinic acid esters, saltsof naphthenic acid, salts of sulfuric acid ester of liquid fatty oilsand salts of alkylallylsulfonic acids; cationic surfactants such assalts of fatty acid amides, quaternary ammonium salts, sulfonium saltsand phophonium; and nonionic surfactants such as polyoxyethylene alkylethers, polyoxyethylene alkyl esters, sorbitan alkyl esters andpolyoxyethylene sorbitan alkyl esters.

The amount of these dispersants added is preferably in the range of 0.2to 20% by weight, still preferably in the range of 1 to 10% by weight,based on the ink.

Although the ink used in the method according to the present inventionmay be basically a water-base ink, the ink preferably contains awater-soluble organic solvent in addition to water (preferablyion-exchanged water) as a solvent. Preferred examples of thewater-soluble organic solvent include alkyl alcohols having 1 to 5carbon atoms such as methyl alcohol, ethyl alcohol, n-propyl alcohol,isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, tert-butylalcohol and isobutyl alcohol; amides such as dimethylformamide anddimethylacetamide; ketones or keto alcohols such as acetone anddiacetinyl alcohol; ethers such as tetrahydrofuran and dioxane; alkyleneglycols of which the alkylene group has 2 to 6 carbon atoms, such asethylene glycol, propylene glycol, triethylene glycol, diethyleneglycol, 1,2,6-hexanetriol, thiodiglycol and hexylene glycol; glycerin;polyalkylene glycols such as polyethylene glycol and polypropyleneglycol; lower alkyl ethers of polyhydric alcohols, such as ethyleneglycol monomethyl (or ethyl) ether, diethylene glycol monomethyl (orethyl) ether and triethylene glycol monomethyl (or ethyl) ether;sulfolane; pyrrolidone; N-methyl-2-pyrrolidone;1,3-dimethyl-2-imidazolidinone; 1,5-pentanediol; and mixtures of theabove organic solvents. The addition of polyhydric alcohols isparticularly preferred from the viewpoint of preventing nozzles fromclogging. This is because the polyhydric alcohols prevent evaporation ofwater in the ink, which prevents the occurrence of a precipitate in thenozzles at their tips. Particularly preferred examples of thewater-soluble organic solvent include polyhydric alcohols, such asdiethylene glycol, and lower alkyl ethers of polyhydric alcohols, suchas triethylene glycol monomethyl (or ethyl) ether. The amount of thesewater-soluble organic solvent added is preferably in the range of about3 to 80% by weight, still preferably in the range of about 3 to 50% byweight, based on the ink.

Still preferably, the black ink contains a polyhydric alcohol incombination with a monohydric alcohol. This prevents the penetration anddispersion of an excessive amount of the ink into the recording mediumto suppress blurring. This enables high-quality printing to be realizedin plain paper. The amount of the monohydric alcohol added is preferablyin the range of about 0.5 to 10% by weight based on the ink, and theamount of the polyhydric alcohol added is preferably in the range of 0.5to 15% by weight based on the ink.

According to a further embodiment of the present invention, when apigment is used as the colorant, it is preferred for the ink used in themethod according to the present invention to contain a resin emulsioncomprising a water-insoluble resin. The term "resin emulsion" usedherein is intended to mean an emulsion comprising water as a continuousphase and the following resin component as a dispersed phase. Examplesof the resin component as the dispersed phase include polyacrylic acidesters, polymethacrylic esters, acrylic resin, vinyl acetate resin,styrene-butadiene resin, vinyl chloride resin and acrylic-styrene resin.

According to a further preferred embodiment of the present invention,this resin is a polymer having both a hydrophilic portion and ahydrophobic portion. Although the particle diameter of the resincomponent is not particularly limited so far as the emulsion is formed,it is preferably about 150 nm or less, still preferably in the range ofabout 5 to 100 nm.

The above resin emulsions can be prepared by mixing the resin particlesoptionally together with a surfactant into water. For example, anemulsion of an acrylic resin or a styrene-acrylic resin can be preparedby mixing an (meth)acrylic ester or styrene, an (meth)acrylic ester andoptionally together with (meth)acrylic acid and a surfactant in water.In general, the mixing ratio of the resin component to the surfactant ispreferably in the range of about 10:1 to 5:1. When the amount of thesurfactant used is smaller than the above range, it may be difficult tosuccessfully prepare an emulsion. On the other hand, when it exceeds theabove range, there may be a tendency that the water resistance of theink is lowered or the penetrability is deteriorated. Although thesurfactant is not particularly limited, preferred examples thereofinclude anionic surfactants (for example, sodiumdodecylbenzenesulfonate, sodium laurate and ammonium salt ofpolyoxyethylene alkyl ether sulfate), nonionic surfactants (for example,polyoxyethylene alkyl ether, polyoxyethylene alkyl ester,polyoxyethylene sorbitan fatty acid ester, polyoxyethylene alkylphenylether, polyoxyethylene alkylamine and polyoxyethylene alkylamide). Theymay be used alone or in the form of a mixture of two or more of them.

Known resin emulsions may be used as the resin emulsion, and resinemulsions described in, for example, Japanese Patent Publication No.1426/1987, Japanese Patent Laid-Open Nos. 56573/1991, 79678/1991,160068/1991 and 18462/1992 and the like, as such, may be used.

It is also possible to employ commercially available resin emulsions,and examples thereof include Microgel E-1002 and E-5002 (astyrene-acrylic resin emulsion manufactured by Nippon Paint Co., Ltd.),Voncoat 4001 (an acrylic resin emulsion manufactured by Dainippon Inkand Chemicals, Inc.), Voncoat 5454 (a styrene-acrylic resin emulsionmanufactured by Dainippon Ink and Chemicals, Inc.), SAE1014 (astyrene-acrylic resin emulsion manufactured by Nippon Zeon Co., Ltd.)and Saivinol SK200 (an acrylic resin emulsion manufactured by SaidenChemical Industry Co., Ltd.).

Furthermore, the ink used in the method according to the presentinvention may contain a component selected from saccharides and theirderivatives and polyols having five or more hydroxyl groups.

According to a further preferred embodiment of the present invention,the black ink used in the method according to the present inventionpreferably has a contact angle with the recording medium of 70° to 113°as measured 10 sec after dropping. The term "contact angle" used hereinis intended to mean an angle that, when a liquid is dropped on thesurface of a solid, the tangent line to the liquid makes with the solidsurface at a point of intersection of three phases of gas-liquid-solid.The contact angle in the above range is advantageous particularly whenrecording paper having a stockigt sizing degree of 5 sec or more is usedas the recording medium. For example, the present inventors havemeasured the stockigt sizing degree of plain paper commonly used in inkjet recording according to Japanese Industrial Standard (JIS) 8122. As aresult, for example, the stockigt sizing degree was 6 sec for4024.3R721™ paper manufactured by Xerox Corp., 41 sec for 10.3R54™ papermanufactured by Xerox Corp., 26 sec for XEROX-P™ paper manufactured byFuji Xerox Co., Ltd. and 25 sec for Fine PPC paper™ manufactured byKishu Paper Co., Ltd. From these results, it is apparent that thestockigt sizing degree of recording paper commonly used in ink jetrecording is 5 sec or more. Therefore, the method according to thepresent invention is advantageous also in that it, as such, can beapplied to the conventional recording paper.

In the color ink used in the method according to the present invention,it is preferred to add a surfactant for the purpose of modifying thesurface tension of the ink. Particularly preferred examples of thesurfactant include acetylene glycol surfactants described in JapanesePatent Publication No. 6752/1983 and Japanese Patent Laid-Open No.139964/1988. Specific examples of the acetylene glycol surfactants asthe particularly preferred surfactant include compounds represented bythe following general formula (I): ##STR1## wherein R represents a C₁₋₆alkyl group, preferably a methyl, ethyl, n-propyl or iso-butyl group, mand n are each 0 or an integer of 1 or more with m+n being preferablyless than 30.

The amount of these surfactants added is preferably in the range of 0.01to 10% by weight, still preferably in the range of 0.5 to 5% by weight,based on the ink. When the amount of the surfactant added is smallerthan the above range, the dissolution stability and quick dryingproperty of the ink may be unfavorably deteriorated. On the other hand,when it exceeds the above range, the ink may be become liable to foam,which often unfavorably deteriorates the quality of print and jettingstability.

According to a further preferred embodiment of the present invention,the ink used in the present invention contain an acetylene glycol incombination with a monohydric alcohol. This enables the flow of theblack ink into the color ink region to be more effectively prevented, sothat a sharp color image can be provided. The amount ratio of acetyleneglycol to monohydric alcohol is preferably in the range of 1:1 to 1:10.

If necessary, the ink used in the method according to the presentinvention may includes, for example, dispersants, surfactants, viscositymodifiers, surface tension modifiers, resistivity modifiers, pHadjusters, antioxidants, fungicides, chelating agents. Although thecontent of these additives may be properly determined depending upon thepurpose of addition, it is generally suitable for the content to be inthe range of 0.01 to 5% by weight.

EXAMPLES

The present invention will now be described in more detail withreference to the following Examples and Comparative Examples, though itis not limited to these Examples.

In the Examples and Comparative Examples, "%" is "% by weight" unlessotherwise noted. "Surfynol" used herein is an acetylene glycolmanufactured by Nissin Chemical Industry Co., Ltd. Surfynol 82 is acompound represented by the formula (I) wherein R represents ethyl, mand n are 0 (zero), Surfynol TG a compound represented by the formula(I) wherein R represents iso-butyl and m and n are 0 (zero), Surfynol440 a compound represented by the formula (I) wherein R representsiso-butyl and m+n=3.5, and Surfynol 465 a compound represented by theformula (I) wherein R represents iso-butyl and m+n=10.

Example A

Inks having compositions shown in Table 1 were prepared according to aconventional method. Specifically, components for constituting thecompositions were mixed with one another, and the mixtures weresufficiently stirred at room temperature for dissolution and filteredwith a 0.8-μm membrane filter to provide inks.

                                      TABLE 1                                     __________________________________________________________________________              Combination of Inks                                                           I              II                                                   Composition                                                                             Black                                                                            Yellow                                                                            Magenta                                                                            Cyan                                                                             Black                                                                            Yellow                                                                            Magenta                                                                            Cyan                                     __________________________________________________________________________    Colorant                                                                      Direct Black 19                                                                         2.0                                                                 Acid Yellow 23                                                                             3.0                                                              Acid Red 52      3.0                                                          Acid Blue 9           3.0                                                     Direct Black 154         2.0                                                  Direct Yellow 86            3.0                                               Direct Red 227                  3.0                                           Direct Blue 199                      3.0                                      Solvent                                                                       Glycerin  4.0                                                                              10.0                                                                              10.0 10.0                                                                             4.0                                                                              20.0                                                                              20.0 20.0                                     Polyethylene 10.0                                                                              10.0 10.0                                                    Glycol #200                                                                   Ethanol   5.0                                                                 n-Propanol               3.0                                                  Additive                                                                      Surfynol TG  0.4 0.4  0.4                                                     Surfynol 82  2.0 2.0  2.0                                                     Surfynol 440                1.0 1.0  1.0                                      Proxel XL-2                                                                             0.3                                                                              0.3 0.3  0.3                                                                              0.3                                                                              0.3 0.3  0.3                                      Ion-exchanged water                                                                     88.7                                                                             74.3                                                                              74.3 74.3                                                                             90.7                                                                             75.7                                                                              75.7 75.7                                     Surface tension                                                                         57.3                                                                             31.2                                                                              30.4 29.7                                                                             50.6                                                                             30.4                                                                              29.9 30.0                                     (dyn/cm, 20° C.)                                                       __________________________________________________________________________              Combination of Inks                                                           III            IV                                                   Composition                                                                             Black                                                                            Yellow                                                                            Magenta                                                                            Cyan                                                                             Black                                                                            Yellow                                                                            Magenta                                                                            Cyan                                     __________________________________________________________________________    Colorant                                                                      Direct Black 154                                                                        2.0                                                                 Direct Black 168         2.0                                                  Food Black 2                                                                  Acid Red 52      2.0                                                          Acid Red 249                    3.0                                           Direct Red 227                                                                Acid Yellow 23                                                                             3.0            3.0                                               Direct Yellow 86                                                              Acid Blue 9           2.0            2.5                                      Direct Blue 199                                                               Solvent                                                                       Glycerin  5.0                                                                              15  15   15    12  12   12                                       Diethylene glycol                                                                          10  10   10 5.0                                                                              10  10   10                                       Ethylene glycol                                                               Ethanol   4.0                                                                 n-Propanol               3.0                                                  Additive                                                                      Surfynol 465 1.0 1.0  1.0   1.5 1.5  1.5                                      Surfynol TG                                                                   Proxel XL-2                                                                             0.3                                                                              0.3 0.3  0.3                                                                              0.3                                                                              0.3 0.3  0.3                                      Ion-exchanged water                                                                     88.7                                                                             70.7                                                                              71.7 71.7                                                                             89.7                                                                             73.2                                                                              73.2 73.7                                     Surface tension                                                                         54.3                                                                             28.5                                                                              28.6 28.8                                                                             50.4                                                                             26.4                                                                              26.9 26.8                                     (dyn/cm, 20° C.)                                                       __________________________________________________________________________              Combination of Inks                                                           V              VI                                                   Composition                                                                             Black                                                                            Yellow                                                                            Magenta                                                                            Cyan                                                                             Black                                                                            Yellow                                                                            Magenta                                                                            Cyan                                     __________________________________________________________________________    Colorant                                                                      Direct Black 154         2.0                                                  Direct Black 168                                                                        2.5                                                                 Food Black 2                                                                  Acid Red 52                                                                   Acid Red 249     3.0                                                          Direct Red 227                  2.5                                           Acid Yellow 23                                                                             2.5                                                              Direct Yellow 86            2.0                                               Acid Blue 9                                                                   Direct Blue 199       3.0            3.0                                      Solvent                                                                       Glycerin  5.0                                                                              20  20   20 5.0                                                                              10  10   10                                       Diethylene glycol                                                                          10  10   10    10  10   10                                       Ethylene glycol          2.0                                                                              3   3    3                                        Ethanol   5.0                                                                 n-Propanol               4.0                                                  Additive                                                                      Surfynol 465 1.0 1.0  1.0   1.2 1.2  1.2                                      Surfynol TG                                                                   Proxel XL-2                                                                             0.3                                                                              0.3 0.3  0.3                                                                              0.3                                                                              0.3 0.3  0.3                                      Ion-exchanged water                                                                     87.2                                                                             66.2                                                                              65.7 65.7                                                                             86.7                                                                             73.5                                                                              73.0 72.5                                     Surface tension                                                                         52.4                                                                             28.7                                                                              28.3 28.5                                                                             53.5                                                                             27.1                                                                              27.0 26.9                                     (dyn/cm, 20° C.)                                                       __________________________________________________________________________              Combination of Inks                                                           VII                                                                 Composition                                                                             Black                                                                            Yellow                                                                            Magenta                                                                            Cyan                                                    __________________________________________________________________________    Colorant                                                                      Direct Black 154                                                              Direct Black 168                                                              Food Black 2                                                                            3.0                                                                 Acid Red 52      2.0                                                          Acid Red 249                                                                  Direct Red 227                                                                Acid Yellow 23                                                                Direct Yellow 86                                                                           2.5                                                              Acid Blue 9           2.5                                                     Direct Blue 199                                                               Solvent                                                                       Glycerin     10  10   10                                                      Diethylene glycol                                                                       7.0                                                                              15  15   15                                                      Ethylene glycol                                                               Ethanol   4.0                                                                 n-Propanol                                                                    Additive                                                                      Surfynol 465 0.8 0.8  0.8                                                     Surfynol TG  0.2 0.2  0.2                                                     Proxel XL-2                                                                             0.3                                                                              0.3 0.3  0.3                                                     Ion-exchanged water                                                                     85.7                                                                             71.2                                                                              71.7 71.2                                                    Surface tension                                                                         54.7                                                                             30.1                                                                              31.2 30.5                                                    (dyn/cm, 20° C.)                                                       __________________________________________________________________________

Evaluation of Inks

These inks were evaluated as follows by means of an ink jet recordingdevice (manufactured by Seiko Epson Corporation, jetting nozzle: 30 μm,drive voltage of piezoelectric element: 80 V, drive frequency: 3 kHz,resolution: 360 dpi, 48 nozzles, on-demand type). The results were asgiven in Table 2.

Evaluation A1

A yellow ink was first printed on commercially available PPC paper(XEROX-PTM manufactured by Fuji Xerox Co., Ltd.) in 100% duty printing,and then a black ink was printed thereon. In this case, the printing wasperformed with the ratio of the amount of black ink to yellow ink perdot being varied as specified in Table 2.

In Comparative Example A3, the yellow ink was not printed on a portionto be printed with the black ink, that is, so that there was no portionwhere the black ink was printed over the yellow ink.

Bleeding due to color mixing of a black ink with a yellow ink wasobserved with the naked eye and evaluated as follows:

Excellent (⊚)--No significant bleeding was observed,

Good (∘)--Slight bleeding which did not deteriorate the whole image wasobserved,

Slightly poor (Δ)--Significant bleeding was observed, and

Poor (x)--Remarkable bleeding which deteriorated the whole image wasobserved.

Evaluation A2

The inks were evaluated by the time required to dry up a print that wasformed in the same manner as that of Evaluation A1 to such a degree thata piece of paper that was the same as the recording paper of the printwas not stained with the ink upon putting on and pressing for one secondto the print. The results were evaluated according to the followingcriteria:

Excellent (⊚)--5 sec or less,

Good (∘)--5 sec to less than 30 sec,

Slightly poor (Δ)--30 sec to 1 min, and

Poor (x)--1 min or more.

Evaluation A3

A black ink was printed over a yellow ink in the same manner as that ofEvaluation A1. A diameter of dot formed by the black ink was comparedwith diameters of dots separately formed on an identical recording paperrespectively with a yellow ink, a magenta ink and a cyan ink. Theresults were evaluated according to the following criteria. The dotdiameters of the three color inks were same as one another.

Excellent (⊚)--The size of the black dot was substantially the same asthat of the color dot, and

Poor (x)--The size of the black dot was significantly different fromthat of the color dot.

                                      TABLE 2                                     __________________________________________________________________________             Combination                                                                         Dot weight ratio of                                                                       Recording                                                                           Evaluation                                                                         Evaluation                                                                         Evaluation                                  of Inks                                                                             black ink to yellow ink                                                                   method                                                                              A1   A2   A3                                 __________________________________________________________________________    Example                                                                             A1 I     10:1              ◯                                                                      ◯                                                                      ⊚                         A2 I     8:1               ◯                                                                      ◯                                                                      ⊚                         A3 I     5:1               ⊚                                                                   ⊚                                                                   ⊚                         A4 I     3:1               ⊚                                                                   ⊚                                                                   ⊚                         A5 I     1:1               ◯                                                                      ⊚                                                                   ⊚                         A6 II    7:1               ◯                                                                      ◯                                                                      ⊚                         A7 II    4:1         Printed                                                                             ◯                                                                      ◯                                                                      ⊚                         A8 II    2:1         with  ⊚                                                                   ⊚                                                                   ⊚                         A9 III   6:1         black ◯                                                                      ◯                                                                      ⊚                         A10                                                                              IV    3:1         ink   ⊚                                                                   ⊚                                                                   ⊚                         A11                                                                              V     5:1         over  ⊚                                                                   ⊚                                                                   ⊚                         A12                                                                              VII   4:1         yellow                                                                              ⊚                                                                   ⊚                                                                   ⊚                         A13                                                                              VIII  1.5:1       ink.  ◯                                                                      ⊚                                                                   ⊚                         A14                                                                              III   2:1               ⊚                                                                   ⊚                                                                   ⊚                         A15                                                                              V     3:1               ⊚                                                                   ⊚                                                                   ⊚                         A16                                                                              VI    3.5:1             ⊚                                                                   ⊚                                                                   ⊚                   Comparative                                                                         A1 I     15:1              Δ                                                                            Δ                                                                            X                                  Example                                                                             A2 I     0.5:1             ◯                                                                      ⊚                                                                   X                                        A3 I     1:1               X    X    X                                        A4 III   4:1         not   X    X    X                                        A5 III   5:1         overlapped                                                                          X    X    X                                        A6 III   2:1               X    X    X                                  __________________________________________________________________________

Example B

Inks having the following compositions were prepared.

    ______________________________________                                        Black ink Bl                                                                  ______________________________________                                        Carbon black MA-100  5%                                                       (manufactured by Mitsubishi                                                   Kasei Corp.)                                                                  Polyvinyl pyrrolidone                                                                              3%                                                       (Mw = 40,000; manufactured by                                                 Tokyo Chemical Industry Co., Ltd.)                                            Acrylic acid/acrylonitrile copolymer                                                               0.3%                                                     Glycerin             5%                                                       Ethanol              5%                                                       Water                Balance                                                  ______________________________________                                    

Carbon black, acrylic acid/acrylonitrile copolymer and water were mixedand dispersed in a paint shaker for 30 min or more until the particlediameter was confirmed to become 1 μm or less under a microscope.Polyvinyl pyrrolidone was added to the dispersion, and they were furtherstirred for 30 min to mix them with each other. The dispersion wasfiltered under pressure with a 5-μm membrane filter to remove coarseparticles. Glycerin and ethanol were added to the filtrate, and themixture was stirred for 5 min to provide a black ink having an averageparticle diameter of 0.06 μm and a pH value of 7.

    ______________________________________                                        Black ink B2                                                                  ______________________________________                                        Carbon black MA-11   5%                                                       (manufactured by Mitsubishi                                                   Kasei Corp.)                                                                  Polyvinyl pyrrolidone                                                                              3%                                                       (Mw = 160,000; manufactured by                                                Tokyo Chemical Industry Co., Ltd.)                                            Polyoxyethylene compound                                                                           0.5%                                                     Propylene glycol     13%                                                      1-Butanol            8%                                                       Water                Balance                                                  ______________________________________                                    

A black ink having an average pigment particle diameter of 0.08 μm wasprepared in the same manner as that of the black ink B1.

    ______________________________________                                        Black in B3                                                                   ______________________________________                                        Carbon black MA-100       3%                                                  Polyvinyl alcohol B03     0.5%                                                (manufactured by Denki Kagaku                                                 Kogyo K.K.)                                                                   Voncoat 4001              2%                                                  (acrylic resin emulsion having a resin component content                      of 50%; manufactured by Dainippon Ink and Chemicals,                          Inc.)                                                                         Sucrose                   5%                                                  Diethylene glycol         10%                                                 n-Propanol                2%                                                  Water                     Balance                                             ______________________________________                                    

All the above components except for glycerin and n-propanol weredispersed together with zirconium beads (diameter: 1.7 mm, amount: 1.5times by weight that of the mixture) in a sand mill (manufactured byYasukawa Seisakusho K. K.) for 2 hr. After the zirconium beads wereremoved, glycerin and n-propanol were added. The mixture was stirred atroom temperature for 20 min. The stirred mixture was filtered through a5-μm membrane filter to provide a black ink having an average pigmentparticle diameter of 0.1 μm.

    ______________________________________                                        Black ink B4                                                                  ______________________________________                                        Carbon black MA-11  5%                                                        Styrene/acrylic acid copolymer                                                                    0.8%                                                      Microgel E-1002     1%                                                        Sucrose             1%                                                        Ethylene glycol     6%                                                        1-Propanol          6%                                                        Water               80.2%                                                     ______________________________________                                    

A black ink having an average pigment particle diameter of 0.3 μm wasprepared in the same manner as that of the black ink B3.

    ______________________________________                                        Black ink B5                                                                  ______________________________________                                        C.I. Direct Black 19                                                                           3%                                                           Glycerin         5%                                                           Ethanol          5%                                                           Water            Balance                                                      ______________________________________                                    

The above components were mixed together and stirred at room temperaturefor 2 hr. The mixture was filtered under a pressure of 2 kg/cm² with a0.8-μm membrane filter to provide an ink.

    ______________________________________                                        Black ink B6                                                                  ______________________________________                                        Carbon black (REVEN 150)                                                                           6%                                                       (manufactured by Columbian Carbon                                             Co., Ltd.)                                                                    Polyvinyl alcohol B03                                                                              6%                                                       Polyethylene oxide   0.3%                                                     Polyethylene glycol  8%                                                       Water                Balance                                                  ______________________________________                                    

The average pigment particle diameter was 0.085 μm.

Color inks 1 to 4 having the following respective compositions wereprepared in the same manner as that of the black ink 5. Surfynol TG andSurfynol 82 are an acetylene glycol manufactured by Nissin ChemicalIndustry Co., Ltd.

    ______________________________________                                        Color ink B1                                                                  ______________________________________                                        Dye             3%                                                            Diethylene glycol                                                                             10%                                                           Surfynol 82     3%                                                            Surfynol TG     0.5%                                                          Water           Balance                                                       ______________________________________                                    

With respect to the dye in the color ink B1, C.I. Acid Yellow 23 as ayellow ink, C.I. Direct Red 9 as a magenta ink, and C.I. Direct Blue 86as a cyan ink were employed, respectively.

    ______________________________________                                        Color ink B2                                                                  ______________________________________                                        Dye             3%                                                            Triethylene glycol                                                                            10%                                                           Surfynol 82     3%                                                            Surfynol TG     0.5%                                                          Water           Balance                                                       ______________________________________                                    

With respect to the dye in the color ink B2, C.I. Direct Yellow 86 as ayellow ink, C.I. Acid Red 254 as a magenta ink, and C.I. Acid Blue 9 asa cyan ink were employed, respectively.

    ______________________________________                                        Color ink B3                                                                  ______________________________________                                        Dye             3%                                                            Diethylene glycol                                                                             10%                                                           Glycerin        10%                                                           Surfynol 82     3%                                                            Surfynol TG     0.5%                                                          Water           Balance                                                       ______________________________________                                    

With respect to the dye in the color ink B3, C.I. Acid Yellow 23 as ayellow ink, C.I. Acid Red 52 as a magenta ink, and C.I. Direct Blue 199as a cyan ink were employed, respectively.

    ______________________________________                                        Color ink B4                                                                  ______________________________________                                        Dye             2%                                                            Diethylene glycol                                                                             10%                                                           Glycerin        15%                                                           Surfynol 465    2%                                                            Water           Balance                                                       ______________________________________                                    

With respect to the dye in the color ink B4, C.I. Direct Yellow 86 as ayellow ink, C.I. Acid Red 254 as a magenta ink, and C.I. Acid Blue 9 asa cyan ink were employed, respectively.

    ______________________________________                                        Color ink B5                                                                  ______________________________________                                        Dye             3%                                                            Diethylene glycol                                                                             10%                                                           Water           Balance                                                       ______________________________________                                    

With respect to the dye in the color ink B5, C.I. Acid Yellow 23 as ayellow ink, C.I. Acid Red 254 as a magenta ink, and C.I. Direct Blue 86as a cyan ink were employed, respectively.

Surface Tension and Viscosity of Inks

The black inks and color inks thus obtained were subjected tomeasurement of surface tension at 25° C. with an HLV-ST surface tensionbalance (manufactured by Kyowa Interface Science Co., Ltd.) andviscosity at 20° C. with a B-type viscometer No. 1 rotor (manufacturedby Tokyo Keiki Co., Ltd.). The results were as shown in Table 3.

                  TABLE 3                                                         ______________________________________                                                      Surface tension                                                                          Viscosity                                            Inks          dyn/cm     mPa.sec                                              ______________________________________                                        Black ink B1  54         3.2                                                  Black ink B2  55         3.7                                                  Black ink B3  56         3.3                                                  Black ink B4  53         2.2                                                  Black ink B5  53         1.9                                                  Black ink B6  55         3.4                                                  Color ink B1                                                                  Yellow ink    27         1.8                                                  Magenta ink   26         1.8                                                  Cyan ink      26         1.9                                                  Color ink B2                                                                  Yellow ink    26         1.9                                                  Magenta ink   26         1.9                                                  Cyan ink      27         2.0                                                  Color ink B3                                                                  Yellow ink    26         2.6                                                  Magenta ink   26         2.6                                                  Cyan ink      26         2.6                                                  Color ink B4                                                                  Yellow ink    27         2.9                                                  Magenta ink   26         2.9                                                  Cyan ink      27         2.9                                                  Color ink B5                                                                  Yellow ink    63         1.6                                                  Magenta ink   64         1.7                                                  Cyan ink      64         1.6                                                  ______________________________________                                    

Evaluation of Inks

Printing was performed with the ink jet recording device used inEvaluation A.

PPC paper (XEROX-P™ manufactured by Fuji Xerox Co., Ltd.), regeneratedpaper (Yamayuri™ manufactured by Honshu Paper Co., Ltd.), bond paper(Gilbert Bond™ (25% cotton paper) manufactured by Mead Corp.) andwood-free paper (OK Wood-Free Paper L™ manufactured by Oji Paper Co.,Ltd.) were used as a recording paper.

The prints were evaluated as follows. The results were as shown in Table4.

Evaluation B1

Printing was performed with the black ink alone, and the quality of theprint was evaluated with the naked eye as follows:

Excellent (⊚)--Neither blurring nor feathering was observed,

Good (∘)--Slight blurring or feathering was observed,

Slightly poor (Δ)--Significant blurring or feathering was observed withletters being still legible, and

Poor (x)--Significant blurring or feathering was observed with lettersbeing illegible.

Evaluation B2

Printing was performed so as for a black ink to be put on a yellow inkin the same manner as that of Evaluation A1. In this case, the amountratio of black ink to yellow ink per dot was 2:1. The quality of theprint was evaluated as follows:

Excellent (⊚)--Neither bleeding nor feathering was observed,

Good (∘)--Slight bleeding or feathering was observed,

Slightly poor (Δ)--Significant bleeding or feathering was observed withletters being still legible, and

Poor (x)--Significant bleeding or feathering was observed with lettersbeing illegible.

Evaluation B3

The reflection OD value of the print provided in Evaluation B2 wasmeasured with Macbeth OCMII (manufactured by Mcbeth), and the resultswere evaluated as follows:

Excellent (⊚)--OD value of 1.3 or more,

Good (∘)--OD value of 1.2 to less than 1.3,

Slightly poor (Δ)--OD value of 1.1 to less than 1.2, and

Poor (x)--OD value of less than 1.1.

Evaluation B4

Color images were formed with the color inks and the black inks. Thequality of the images was evaluated as follows:

High image quality (⊚)--No bleeding attributable to color mixing wasobserved with good color image,

Good image quality (∘)--Slight bleeding attributable to color mixing wasobserved with good color image,

Slightly poor image quality (Δ)--Bleeding attributable to color mixingwas observed with poor color image, and

Poor image quality (x)--Remarkable bleeding attributable to color mixingwas observed with poor color image.

                                      TABLE 4                                     __________________________________________________________________________                   Example                                                                       B1                                                                              B2                                                                              B3                                                                              B4                                                                              B5                                                                              B6                                                                              B7                                                                              B8                                                                              B9                                                                              B10                                                                              B11                                                                              B12                                                                              B13                                                                              B14                                                                              B15                                                                              B16                        Black ink      B1                                                                              B1                                                                              B1                                                                              B2                                                                              B2                                                                              B2                                                                              B3                                                                              B3                                                                              B3                                                                              B1 B2 B3 B4 B4 B4 B4                         Color ink      B1                                                                              B2                                                                              B3                                                                              B1                                                                              B2                                                                              B3                                                                              B1                                                                              B2                                                                              B3                                                                              B4 B4 B4 B1 B2 B3 B4                         __________________________________________________________________________    Evaluation B1                                                                        PPC paper                                                                             ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚                  Recycled paper                                                                        ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚                  Bond paper                                                                            ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚                  Wood-free paper                                                                       ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚           Evaluation B2                                                                        PPC paper                                                                             ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚                  Recycled paper                                                                        ◯                                                                   ◯                                                                   ◯                                                                   ◯                                                                   ◯                                                                   ◯                                                                   ◯                                                                   ◯                                                                   ◯                                                                   ◯                                                                    ◯                                                                    ◯                                                                    ◯                                                                    ◯                                                                    ◯                                                                    ◯                     Bond paper                                                                            ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚                  Wood-free paper                                                                       ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚           Evaluation B3                                                                        PPC paper                                                                             ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚                  Recycled paper                                                                        ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚                  Bond paper                                                                            ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚                  Wood-free paper                                                                       ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚           Evaluation B4                                                                        PPC paper                                                                             ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚                  Recycled paper                                                                        ◯                                                                   ◯                                                                   ◯                                                                   ◯                                                                   ◯                                                                   ◯                                                                   ◯                                                                   ◯                                                                   ◯                                                                   ◯                                                                    ◯                                                                    ◯                                                                    ◯                                                                    ◯                                                                    ◯                                                                    ◯                     Bond paper                                                                            ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚                  Wood-free paper                                                                       ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚                                                                 ⊚                          Comparative Example                                                           B1                                                                              B2                                                                              B3                                                                              B4                                                                              B5                                                                              B6                                                   Black ink      B1                                                                              B2                                                                              B3                                                                              B4                                                                              B5                                                                              B6                                                   Color ink      B5                                                                              B5                                                                              B5                                                                              B5                                                                              B5                                                                              B5                                                   __________________________________________________________________________    Evaluation B1                                                                        PPC paper                                                                             ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ◯                                                                   Δ                                                     Recycled paper                                                                        ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ◯                                                                   Δ                                                     Bond paper                                                                            ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ◯                                                                   Δ                                                     Wood-free paper                                                                       ⊚                                                                ⊚                                                                ⊚                                                                ⊚                                                                ◯                                                                   Δ                                              Evaluation B2                                                                        PPC paper                                                                             X X X X X X                                                           Recycled paper                                                                        X X X X X X                                                           Bond paper                                                                            X X X X X X                                                           Wood-free paper                                                                       X X X X X X                                                    Evaluation B3                                                                        PPC paper                                                                             X X X X X X                                                           Recycled paper                                                                        X X X X X X                                                           Bond paper                                                                            X X X X X X                                                           Wood-free paper                                                                       X X X X X X                                                    Evaluation B4                                                                        PPC paper                                                                             X X X X X X                                                           Recycled paper                                                                        X X X X X X                                                           Bond paper                                                                            X X X X X X                                                           Wood-free paper                                                                       X X X X X X                                                    __________________________________________________________________________

Example C

Inks having compositions shown in Table 5 were prepared by aconventional method. All the numerical values in the table are % byweight.

Surface Tension and Contact Angle of Inks

The inks thus obtained were subjected to measurement of surface tensionin the same manner as that of Example B.

In addition, the inks were dropped on recording paper (P paper™manufactured by Fuji Xerox Co., Ltd.; and 4024 paper™ manufactured byXerox Corp.), and the contact angle 10 sec after the dropping wasmeasured with an automatic contact angle measuring device CA-Z(manufactured by Kyowa Interface Science Co., Ltd.).

The results were as shown in Table 5.

                                      TABLE 5                                     __________________________________________________________________________                        Black ink            Color ink                            Composition         C1 C2 C3 C4 C5 C6 C7 C1 C2 C3                             __________________________________________________________________________    Colorant                                                                           C.I. Direct Black 19                                                                         1.5                                                                              1.5                                                         C.I. Direct Black 154                                                                              1.5                                                                              1.5      3.5                                          C.I. Direct Black 168      1.5                                                                              1.0                                             C.I. Acid Yellow 23                 4.0                                       C.I. Direct Yellow 86                  3.0                                                                              3.0                            Solvent                                                                            Glycerin       5.0      5.0   5.0   20.0                                                                             10.0                                                                             20.0                                2-Pyrrolidone                       10.0                                      Diethylene glycol 5.0                                                                              5.0   5.0   10.0     10.0                                Polyethylene glycol #200         10.0  10.0                                   Diethylene glycol monobutyl ether                                                                        5.0                                                Ethanol        5.0                                                                              5.0   5.0                                                   n-Propanol           5.0   3.0                                           Additive                                                                           Surfynol TG                         0.5                                                                              0.5                                    Surfynol 82             0.5         2.0                                       Surfynol 440                           1.0                                    Surfynol 465                              1.0                                 Sodium dialkysulfonsuccinate     1.0                                     Preservation Proxel XL-2                                                                          0.3                                                                              0.3                                                                              0.3                                                                              0.3                                                                              0.3                                                                              0.3                                                                              0.3                                                                              0.3                                                                              0.3                                                                              0.3                            Solvent Ion-exchanged water                                                                       88.2                                                                             88.2                                                                             88.2                                                                             87.7                                                                             85.2                                                                             93.7                                                                             75.2                                                                             63.2                                                                             75.2                                                                             65.7                           Surface tension (dyn/cm, 20° C.)                                                           54 52 48 45 41 64 28 31 36 28                             __________________________________________________________________________

Evaluation of Inks

Printing was performed with the ink jet recording device used inevaluation A. The prints were evaluated as follows. The results were asshown in Table 6.

Evaluation C1

Printing was performed with the black ink alone, and the quality of theprint was evaluated with the naked eye as follows:

Excellent (⊚)--Neither blurring nor feathering was observed,

Good (∘)--Slight blurring or feathering was observed,

Slightly poor (Δ)--Significant blurring or feathering was observed withletters being still legible, and

Poor (x)--Significant blurring or feathering was observed with lettersbeing illegible.

Evaluation C2

Printing was performed so as for a black ink to be put on a yellow inkin the same manner as that of Evaluation A1. In this case, the amountratio of black ink to yellow ink per dot was 2.5:1. The quality of theprint was evaluated as follows:

Excellent (⊚)--Neither bleeding nor feathering was observed,

Good (∘)--Slight bleeding or feathering was observed,

Slightly poor (Δ)--Significant bleeding or feathering was observed withletters being still legible, and

Poor (x)--Significant bleeding or feathering was observed with lettersbeing illegible.

Evaluation C3

The inks were evaluated by the time required to dry up a print that wasformed in the same manner as that of Evaluation A1 to such a degree thata piece of paper that was the same as the recording paper of the printwas not stained with the ink upon putting on and pressing for one secondto the print. The results were evaluated according to the followingcriteria:

Excellent (⊚)--5 sec or less,

Good (∘)--5sec to less than 30 sec,

Slightly poor (Δ)--30 sec to 1 min, and

Poor (x)--1 min or more.

                                      TABLE 6                                     __________________________________________________________________________                      Contact angle                                                                 (°)                                                                           Evaluation C1                                                                        Evaluation C2                                                       Paper  Paper  Paper                                             Black ink                                                                          Color ink                                                                          Paper P                                                                           4024                                                                             Paper P                                                                           4024                                                                             Paper P                                                                           4204                                                                             Evaluation C3                          __________________________________________________________________________    Example                                                                             C1                                                                              C1   C1   112 110                                                                              ⊚                                                                  ⊚                                                                 ◯                                                                     ◯                                                                    ◯                                C2                                                                              C2   C1   108 104                                                                              ⊚                                                                  ⊚                                                                 ◯                                                                     ◯                                                                    ◯                                C3                                                                              C3   C1    98  92                                                                              ⊚                                                                  ◯                                                                    ◯                                                                     ⊚                                                                 ⊚                             C4                                                                              C4   C2    89  88                                                                              ◯                                                                     ◯                                                                    ⊚                                                                  ⊚                                                                 ⊚                             C5                                                                              C5   C2    76  72                                                                              ◯                                                                     ◯                                                                    ⊚                                                                  ⊚                                                                 ⊚                             C6                                                                              C1   C3   112 110                                                                              ⊚                                                                  ⊚                                                                 ◯                                                                     ◯                                                                    ⊚                             C7                                                                              C2   C3   108 104                                                                              ⊚                                                                  ⊚                                                                 ⊚                                                                  ⊚                                                                 ⊚                             C8                                                                              C3   C3    98  92                                                                              ⊚                                                                  ◯                                                                    ⊚                                                                  ⊚                                                                 ⊚                       Comparative                                                                         C1                                                                              C6   C2   120 115                                                                              ⊚                                                                  ⊚                                                                 X   X  X                                      Example                                                                             C2                                                                              C7   C2    37  22                                                                              X   X  ⊚                                                                  ⊚                                                                 ⊚                       __________________________________________________________________________

Example D

Inks having the following compositions were prepared according to aconventional method. Briefly, components were mixed and were stirred atroom temperature for 2 hr and filtered with a 0.8-μm membrane filterunder a pressure of 2 kg/cm² to provide the inks.

    ______________________________________                                        Black ink D1                                                                  C.I. Direct Black 154                                                                          3%                                                           Glycerin         5%                                                           Ethanol          5%                                                           Ion-exchanged water                                                                            Balance                                                      Black ink D2                                                                  C.I. Food Black 2                                                                              3%                                                           Triethylene glycol                                                                             5%                                                           Methanol         5%                                                           Ion-exchanged water                                                                            Balance                                                      Black ink D3                                                                  C.I. Direct Black 154                                                                          3%                                                           Diethylene glycol                                                                              5%                                                           2-Propanol       5%                                                           Ion-exchanged water                                                                            Balance                                                      Color ink D1                                                                  Dye              3%                                                           Diethylene glycol                                                                              10%                                                          Glycerin         10%                                                          Ethanol          10%                                                          Surfynol 82      0.5%                                                         Surfynol TG      0.5%                                                         Ion-exchanged water                                                                            Balance                                                      ______________________________________                                    

With respect to the dye in the color ink D1, C.I. Acid Yellow 23 as ayellow ink, C.I. Direct Red 9 as a magenta ink, and C.I. Direct Blue 86as a cyan ink were employed, respectively.

    ______________________________________                                        Color ink D2                                                                  ______________________________________                                        Dye              3%                                                           Triethylene glycol                                                                             10%                                                          n-Propanol       10%                                                          Surfynol 82      2%                                                           Surfynol TG      0.5%                                                         Ion-exchanged water                                                                            Balance                                                      ______________________________________                                    

With respect to the dye in the color ink D2, C.I. Direct Yellow 86 as ayellow ink, C.I. Acid Red 254 as a magenta ink, and C.I. Acid Blue 9 asa cyan ink were employed, respectively.

    ______________________________________                                        Color ink D3                                                                  ______________________________________                                        Dye              3%                                                           Diethylene glycol                                                                              10%                                                          Glycerin         10%                                                          Ethanol          10%                                                          Surfynol 82      0.8%                                                         Surfynol TG      0.4%                                                         Ion-exchanged water                                                                            Balance                                                      ______________________________________                                    

With respect to the dye in the color ink D3, C.I. Direct Yellow 86 as ayellow ink, C.I. Acid Red 249 as a magenta ink, and C.I. Direct Blue 86as a cyan ink were employed, respectively.

    ______________________________________                                        Color ink D4                                                                  ______________________________________                                        Dye              3%                                                           Triethylene glycol                                                                             10%                                                          2-Propanol       5%                                                           Surfynol 82      3%                                                           Surfynol TG      0.5%                                                         Ion-exchanged water                                                                            Balance                                                      ______________________________________                                    

With respect to the dye in the color ink D4, C.I. Acid Yellow 23 as ayellow ink, C.I. Acid Red 254 as a magenta ink, and C.I. Direct Blue 199as a cyan ink were employed, respectively.

    ______________________________________                                        Color ink D5                                                                  ______________________________________                                        Dye              3%                                                           Diethylene glycol                                                                              10%                                                          Ethanol          25%                                                          Surfynol 82      3%                                                           Surfynol TG      0.5%                                                         Ion-exchanged water                                                                            Balance                                                      ______________________________________                                    

With respect to the dye in the color ink D5, C.I. Acid Yellow 23 as ayellow ink, C.I. Acid Red 254 as a magenta ink, and C.I. Direct Blue 86as a cyan ink were employed, respectively.

    ______________________________________                                        Color ink D6                                                                  ______________________________________                                        Dye              3%                                                           Diethylene glycol                                                                              10%                                                          Glycerin         10%                                                          2-Propanol       0.5%                                                         Surfynol TG      0.4%                                                         Ion-exchanged water                                                                            Balance                                                      ______________________________________                                    

With respect to the dye in the color ink D6, C.I. Acid Yellow 23 as ayellow ink, C.I. Acid Red 52 as a magenta ink, and C.I. Direct Blue 199as a cyan ink were employed, respectively.

    ______________________________________                                        Color ink D7                                                                  ______________________________________                                        Dye              2%                                                           Diethylene glycol                                                                              10%                                                          Glycerin         15%                                                          Ethanol          5%                                                           Surfynol 465     1.5%                                                         Ion-exchanged water                                                                            Balance                                                      ______________________________________                                    

With respect to the dye in the color ink D7, use was made of C.I. DirectYellow 86 as a yellow ink, C.I. Acid Red 249 as a magenta ink, and C.I.Direct Blue 199 as a cyan ink.

    ______________________________________                                        Color ink D8                                                                  ______________________________________                                        Dye              3%                                                           Diethylene glycol                                                                              10%                                                          Glycerin         10%                                                          2-Propanol       6%                                                           Surfynol TG      0.5%                                                         Ion-exchanged water                                                                            Balance                                                      ______________________________________                                    

With respect to the dye in the color ink D8, C.I. Acid Yellow 23 as ayellow ink, C.I. Acid Red 52 as a magenta ink, and C.I. Direct Blue 199as a cyan ink were employed, respectively.

    ______________________________________                                        Color ink D9                                                                  ______________________________________                                        Dye              3%                                                           Ethylene glycol  10%                                                          Glycerin         10%                                                          n-Propanol       2%                                                           Surfynol 82      3%                                                           Surfynol TG      0.5%                                                         Ion-exchanged water                                                                            Balance                                                      ______________________________________                                    

With respect to the dye in the color ink D9, C.I. Direct Yellow 86 as ayellow ink, C.I. Acid Red 249 as a magenta ink, and C.I. Acid Blue 9 asa cyan ink were employed, respectively.

    ______________________________________                                        Color ink D10                                                                 ______________________________________                                        Dye              3%                                                           Diethylene glycol                                                                              10%                                                          Glycerin         10%                                                          2-Propanol       10%                                                          Ion-exchanged water                                                                            Balance                                                      ______________________________________                                    

With respect to the dye in the color ink D10, C.I. Acid Yellow 23 as ayellow ink, C.I. Acid Red 52 as a magenta ink, and C.I. Direct Blue 199as a cyan ink were employed, respectively.

    ______________________________________                                        Color ink D11                                                                 ______________________________________                                        Dye              3%                                                           Diethylene glycol                                                                              10%                                                          Ion-exchanged water                                                                            Balance                                                      ______________________________________                                    

With respect to the dye in the color ink D11, C.I. Direct Yellow 86 as ayellow ink, C.I. Direct Red 9 as a magenta ink, and C.I. Direct Blue 199as a cyan ink were employed, respectively.

Surface Tension and Viscosity of Inks

The inks thus obtained were subjected to measurement of surface tensionand viscosity in the same manner as that of Example B. The results wereas shown in Table 7.

                                      TABLE 7                                     __________________________________________________________________________                 Surface tension dyn/cm                                                                   Viscosity mRa.sec                                     Black ink D1 55         2.0                                                   Black ink D2 57         2.2      Acetylene glycol:                            Black ink D3 54         2.1      Monohydric alcohol                           __________________________________________________________________________    Color ink D1                                                                         Yellow ink                                                                          27         2.5      1:2.85                                              Magenta ink                                                                         27         2.4                                                          Cyan ink                                                                            28         2.5                                                   Color ink D2                                                                         Yellow ink                                                                          27         2.2      1:4                                                 Magenta ink                                                                         28         2.3                                                          Cyan ink                                                                            27         2.3                                                   Color ink D3                                                                         Yellow ink                                                                          27         2.4      1:8.3                                               Magenta ink                                                                         27         2.4                                                          Cyan ink                                                                            27         2.5                                                   Color ink D4                                                                         Yellow ink                                                                          27         2.1      1:1.43                                              Magenta ink                                                                         28         2.2                                                          Cyan ink                                                                            28         2.2                                                   Color ink D5                                                                         Yellow ink                                                                          26         2.6      1:7.14                                              Magenta ink                                                                         27         2.6                                                          Cyan ink                                                                            26         2.6                                                   Color ink D6                                                                         Yellow ink                                                                          28         2.2      1:1.25                                              Magenta ink                                                                         28         2.1                                                          Cyan ink                                                                            28         2.1                                                   Color ink D7                                                                         Yellow ink                                                                          26         2.9      1:3.3                                               Magenta ink                                                                         27         2.9                                                          Cyan ink                                                                            26         2.9                                                   Color ink D8                                                                         Yellow ink                                                                          27         2.5      1:12                                                Magenta ink                                                                         28         2.5                                                          Cyan ink                                                                            28         2.4                                                   Color ink D9                                                                         Yellow ink                                                                          28         2.3      1:0.57                                              Magenta ink                                                                         28         2.2                                                          Cyan ink                                                                            27         2.2                                                   Color ink D10                                                                        Yellow ink                                                                          48         2.3                                                          Magenta ink                                                                         46         2.3                                                          Cyan ink                                                                            45         2.2                                                   Color ink D10                                                                        Yellow ink                                                                          56         2.1                                                          Magenta ink                                                                         57         2.0                                                          Cyan ink                                                                            56         2.0                                                   __________________________________________________________________________

Evaluation of Inks

Printing was performed with the ink jet recording device used inevaluation A. The prints were evaluated as follows. The results were asshown in Table 8.

Evaluation D1

Printing was performed so as for a black ink to be put on a color ink inthe same manner as that of Evaluation A1. In this case, the amount ratioof black ink to yellow ink per dot was 3:1. The quality of the printswas evaluated in the same manner as that described in connection withevaluation A1.

Evaluation D2

Color images were formed using the color inks and the black inks in thesame manner as that of evaluation B4. The quality of the images wasevaluated in the same manner as that described in connection withevaluation B4.

                  TABLE 8                                                         ______________________________________                                                                 Evaluation                                                                             Evaluation                                         Black ink                                                                            Color ink  D1       D2                                          ______________________________________                                        Example                                                                       D1       D1       D1         ⊚                                                                     ⊚                          D2       D2       D2         ⊚                                                                     ⊚                          D3       D3       D3         ⊚                                                                     ⊚                          D4       D1       D4         ⊚                                                                     ⊚                          D5       D2       D5         ⊚                                                                     ⊚                          D6       D3       D6         ⊚                                                                     ⊚                          D7       D1       D7         ⊚                                                                     ⊚                          D8       D1       D8         ∘                                                                        ∘                             D9       D2       D9         ∘                                                                        ∘                             Comparative                                                                   Example                                                                       D1       D1       D10        x      x                                         D2       D3       D11        x      x                                         ______________________________________                                    

What is claimed is:
 1. A color ink jet recording method for printing ona recording medium containing a portion to be rendered black and a colorportion, the portion to be black being in contact with the color portionin a color image to be formed, said method comprising the steps of:a)printing first at least one color ink on a subportion of the portion tobe black which subportion is in contact with the color portion on therecording medium, whereby the portion to be black is partially printedwith the at least one color ink, b) printing a black ink on the portionto be black which is partially printed with the at least one color inkaccording to the previous step, said at least one color ink having asurface tension at 20° C. of less than 40 dyn/cm and the black inkhaving a surface tension at 20° C. of 40 dyn/cm or more.
 2. Therecording method according to claim 1, wherein said at least one colorink is selected from the group consisting of yellow, magenta and cyaninks.
 3. The recording method according to claim 1, wherein the weightratio of black ink to color ink per dot printed is in the range of 10:1to 1:1.
 4. The recording method according to claim 1, wherein said blackink contains 0.5 to 10% by weight of a monohydric alcohol and 0.5 to 15%by weight of a polyhydric alcohol.
 5. The recording method according toclaim 1, wherein said black ink has the contact angle with the recordingmedium is in the range of 70° to 113° as measured 10 sec after dropping.6. The recording method according to claim 1, wherein said black inkcomprises a pigment as a colorant and said color ink comprises awater-soluble dye as a colorant.
 7. The recording method according toclaim 1, wherein said color ink comprises acetylene glycol.
 8. Therecording method according to claim 7, wherein said color ink comprisesa monohydric alcohol and an acetylene glycol in a weight ratio ofacetylene glycol to monohydric alcohol of 1:1 to 1:10.